Apple's new 12-in. MacBook is a "repair nightmare," as tough on do-it-yourselfers as 2012's first Retina-equipped MacBook Pro, according to iFixit.

"The internals are unnecessarily complex; it's a minefield of pentalobe and tri-wing screws, fragile cables snaked around essential components, and a solidly-glued-down multi-cell battery," iFixit reported on its blog Wednesday. "Tack on the non-upgradeability, and the Retina MacBook is a repair nightmare."

San Luis Obispo, Calif.-based iFixit -- one of the Web's best-known electronics repair firms -- awards repairability scores between 1 and 10 to devices after pulling them apart. It gave the MacBook a "1," the same slapped on the first MacBook Pro with a high-resolution display nearly three years ago. At that time, iFixit said the Retina MacBook Pro was the "least-repairable laptop we've taken apart."

iFixit

The 12-in. MacBook's battery pouches revealed: Remnants of the adhesive can be seen on the lower case on the right.

Apple began selling the 12-in. MacBook on April 10. The ultra-thin and ultra-light notebook -- 15% lighter than the 11-in. MacBook Air, 31% lighter than the 13-in. Air -- starts at $1,299.

iFixit blamed several characteristics of the MacBook for the low score, several of them a litany familiar to DIYers trying to repair Apple's hardware, including tamperproof five-point pentalobe screws, "futuristic pegs and weird spring clips," a hidden battery connector and "nasty adhesive" to affix the form-fitting battery pouches.

About the latter, iFixit said, "This level of precision works well for fitting the largest battery possible, but it doesn't bode well for the idea of battery replacement."

Apple charges $199 for an out-of-warranty battery replacement of the 12-in. MacBook, $70 more than it does for the MacBook Air, and the same price as for the 13-in. and 15-in. Retina MacBook Pro.

Like all Apple laptops, the MacBook also cannot be upgraded by the user -- Apple's far from alone there -- with both RAM and SSD (solid-state drive) soldered to the logic board. The notebook is only available with 8GB of RAM, but customers can choose between models with either a 256GB or 512GB SSD.

iFixit's MacBook teardown, complete with photographs taken at each step, can be found on the company's website.